1. Field of the Invention
The present invention relates to a golf ball having a polyurethane cover and more particularly to a golf ball satisfying both spin performance and abrasion resistance.
2. Description of the Related Art
Conventionally balata covers have been widely employed for a cover of golf balls; however, since the balata covers have a problem that the covers are inferior in abrasion resistance, covers using ionomer resins have been developed as a substitute for the balata covers. The covers using ionomer resins have been used widely owing to excellent processability; however, they have high stiffness and hardness and accordingly, problems of insufficient spin performance and inferior controllability have been pointed out.
Therefore, covers using polyurethanes have been developed as a substitute for a balata cover, since polyurethanes are excellent in spinning performance as compared with ionomer resins. For example, Japanese Patent Publication No 2002-315850 A discloses a golf ball including a center made of one or more layers containing a polybutadiene having a molecular weight of more than about 200,000 and a resilience index of at least about 40, a cover having at least one layer containing a polyurethane blend formed from a prepolymer having 7.5% by weight or less of an unreacted isocyanate group, and at least one thread material disposed between the center and the cover, wherein each thread provides at least one wound layer having at least one strand.